1. Field of the Invention
This invention pertains to electrodes for use in the air-carbon arc cutting and gouging process used in industry for cutting, cleaning, or preparing metals for subsequent fabrication operations. In the hands of a skilled operator, a ferrous material, e.g. steel plate, can be provided with a groove which can subsequently be filled with a weld metal deposit to effect a repair or facilitate a subsequent fabrication operation.
2. Description of the Prior Art
The air-carbon arc cutting and gouging process was first described in U.S. Pat. No. 2,706,236. According to the process as now practiced, a carbon-graphite electrode, normally having a copper coating, is positioned so that an arc can be struck between the electrode and a workpiece. At the same time the arc is initiated, compressed air is caused to flow down one side of the electrode to forcibly remove (blast away) molten metal produced by the effect of the electric arc.
Electrodes suitable for use in the air-carbon arc cutting and gouging process are discussed in detail in U.S. Pat. Nos. 3,303,544; 3,131,290; 3,633,063; and 3,796,853. In all of the prior patents the conventional coating on the electrode is shown to be a thin copper layer. The copper layer is included to increase the conductivity along the length of the electrode and prevent errosion and oxidation of the electrode. The conventional method for applying the coating is by electroplating as is disclosed in U.S. Pat. No. 3,796,853.
Attempts have been made to improve the coatings by providing a multi-layered coating. One such coating is disclosed in Japanese Pat. No. 45-21585 wherein patentee discloses a carbon-graphite electrode having a first coating which is 0.05 millimeters of copper over which is placed a coating of 0.05 millimeters of aluminum. The purpose for the aluminum coating was to prevent deterioration of the copper in aqueous environments.
Conventional air-carbon arc cutting and gouging electrodes are generally produced by electroplating copper on the carbon-graphite electrode blank or substrate. These coatings are porous thus promoting adsorption of moisture from the air as noted in regard to the aluminum coated electrodes set out above. When the electrode is used, the copper-coated electrodes produce fumes of copper thus creating deleterious working conditions for the operator.
Lastly, almost all of the air-carbon arc copper coated electrodes operate at a noise level of between 120 and 125 dbA in normal use. This operation noise level exceeds current safe standards for operators using the air-carbon arc cutting and gouging process.